Search for 7Be in the outburst of four recent novae

Abstract

Following the recent detection of 7Be in the outburst spectra of Classical Novae we report the search for this isotope in the outbursts of four recent bright novae by means of high resolution UVES observations. The 7BeII 313.0583, 313.1228 nm doublet resonance lines are detected in the high velocity components of Nova Mus 2018 and ASASSN-18fv during outburst. On the other hand 7BeII is neither detected in ASASSN-17hx and possibly nor in Nova Cir 2018, therefore showing that the 7BeII is not always ejected in the thermonuclear runaway. Taking into account the 7Be decay we find X(7Be)/X(H) approx 1.5 x10 ^{-5} and 2.2 x 10 ^{-5} in Nova Mus 2018 and ASASSN-18fv, respectively. A value of 7Be/H about 2 x10 ^{-5} is found in 5 out of the 7 extant measurements and it might be considered as a typical 7Be yield for novae. However, this value is almost one order of magnitude larger than predicted by current theoretical models. We argue that the variety of high 7Be/H abundances could be originated in a higher than solar content of 3He in the donor star. The cases with 7Be not detected might be related to a small mass of the WD or to relatively little mixing with the core material of the WD. The 7Be /H, or 7Li/H, abundance is about 4 dex above meteoritic thus confirming the novae as the main sources of 7Li in the Milky Way.

13 pages, 12 figures, accepted MNRAS

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• The Gaia mission
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• Thermohaline mixing: A physical mechanism governing the photospheric composition of low-mass giants
• The VST Photometric Halpha Survey of the Southern Galactic Plane and Bulge (VPHAS+)
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• Observations of Galactic and Extragalactic Novae
• The Gaia-ESO Survey: Galactic evolution of lithium from iDR6
• Light Elements in the Universe
• The GALAH Survey and Symbiotic Stars. I. Discovery and follow-up of 33 candidate accreting-only systems
• 7Be detection in the 2021 outburst of RS Oph
• Detection of ${}^7$Be II in the Classical Nova V5669 Sgr (Nova Sagittarii 2015 No.3)
• An evidence-based assumption that helps to reduce the discrepancy between the observed and predicted ${}^7$Be abundances in novae
• Detection of ${}^7$Be II in the Small Magellanic Cloud
• Novae: An Important Source of Lithium in the Galaxy
• Evolution of lithium in the disc of the Galaxy and the role of novae
• Lithium evolution in the Galactic thin disc from Main-Sequence and early Red-Giant-Branch stars
• Unevolved Li-rich stars at low metallicity: a possible formation pathway through novae
• Shock shaping? Nebular Spectroscopy of Nova V906 Carinae
• Evidence of the gamma-ray counterpart from nova FM Cir with Fermi-LAT
• Viability of novae as sources of Galactic lithium
• 7Be in the outburst of the ONe nova V6595 Sgr
• Time Domain Astronomy with the THESEUS Satellite
• Gaia-Sausage-Enceladus: Lithium evolution from early red-giant-branch and main-sequence stars